U.S. Pat. Nos. 5,626,191 and 6,412,557, incorporated herein in their entirety, disclose in situ combustion processes for producing oil from an underground reservoir (100) utilizing an injection well (102) placed relatively high in an oil reservoir (100) and a production well (103-106) completed relatively low in the reservoir (100). The production well has a horizontal leg (107) oriented generally perpendicularly to a generally linear and laterally extending upright combustion front propagated from the injection well (102). The leg (107) is positioned in the path of the advancing combustion front. Air, or other oxidizing gas, such as oxygen-enriched air, is injected through wells 102, which may be vertical wells, horizontal wells or combinations of such wells.
The process of U.S. Pat. No. 5,626,191 is called “THAI™”, an acronym for “toe-to-heel air injection” and the process of U.S. Pat. No. 6,412,557 is called “Capri™”, the Trademarks being held by Archon Technologies Ltd., a subsidiary of Petrobank Energy and Resources Ltd., Calgary, Alberta, Canada.
What is needed is one or more methods to increase productivity when undertaking oil recovery from an underground reservoir by the toe-to-heel in situ combustion process employing horizontal production wells.